Before the present invention, circuit board assemblies have been known. However, in some cases a relatively large circuit board may be required for some assemblies, such as 30 inches by 12 inches. Although this may be the ideal size of the boards for certain uses, the large boards encounter many difficulties.
First, the larger and more complex a circuit board assembly may be, it is more difficult to test the board for errors. Large boards are more difficult to assemble and test on available production fixtures and the tooling available. Also, the large boards have a tendency to warp, and therefor become a quality problem. The large boards tend to flex and thus can't be used with certain components without introducing potential quality problems due to cracked components and loose solder joints.
In addition, subsets of the board design may need to be upgradable because the technology has changed, but replacing the large boards for this purpose can be very costly. Design modifications may need to be made on a subset of the main assembly which may cause scrapping of the whole assembly. Such methods of using the boards may also thicken the board thereby occupying more than one slot in a system back plane.